Compaction stimulates denitrification in an urban park soil using 15N tracing technique

Abstract

Soils in urban areas are subjected to compaction with accelerating urbanization. The effects of anthropogenic compaction on urban soil denitrification are largely unknown. We conducted a study on an urban park soil to investigate how compaction impacts denitrification. By using 15 N labeling method and acetylene inhibition technique, we performed three coherent incubation experiments to quantify denitrification in compacted soil under both aerobic and anaerobic conditions. Uncompacted soil was set as the control treatment. When monitoring soil incubation without extra substrate, higher nitrous oxide (N 2 O) flux and denitrification enzyme activity were observed in the compacted soil than in the uncompacted soil. In aerobic incubation with the addition of K 15 NO 3 , N 2 O production in the compacted soil reached 10.11 ng N h −1 g −1 as compared to 0.02 ng N h −1 g −1 in the uncompacted soil. Denitrification contributed 96 % of the emitted N 2 O in the compacted soil and 36 % of the emitted N 2 O in the uncompacted soil; total denitrification rate was higher in the compacted soil (up to 79.35 ng N h −1 g −1 ) than in the uncompacted soil (0.11 ng N h −1 g −1 ). Under anaerobic incubation with the addition of K 15 NO 3 , no statistical difference in total N losses and 15 N-(N 2 O+N 2 ) flux between the uncompacted soil and the compacted soil was detected. Compaction promoted soil denitrification and may impact urban N biogeochemical cycling.

The effects of urine nitrogen application rate on nitrogen transformations in grassland soils

“…Urine application can increase pH due to hydrolysis of organic matter, increasing both carbon and N turnover (Monaghan and Barraclough, 1993;Selbie et al, 2015). Other differences between soils, such as P availability (Mehnaz and Dijkstra, 2016) and soil structure (Li et al, 2014) have been suggested previously as significantly influencing N dynamics, particularly for in situ studies.…”

Impact of vegetation harvesting on nutrient removal and plant biomass quality in wetland buffer zones

“…We found a high N removal efficiency in the mown site m1 (Table 1), which might be explained either by N removal with hay or due to soil compaction by the mowing machinery, which may stimulate denitrification by lowering the oxygen content in soil pores (Li et al, 2014). However, this does not have to be a result of mowing, as N removal in the unmown sites was also substantial.…”

“…Another potential interaction is caused by soil compaction due to the pressure exerted by mowing machinery. Soil compaction has been reported to stimulate denitrification by increasing water-filled pore space in the soil, thereby lowering the oxygen supply (Li et al, 2014. However, such changes might promote internal release of P due to favoured reduction of redox-sensitive iron(III)-P binding forms (Zak et al, 2018).…”

Increased copper levels inhibit denitrification in urban soils

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